In industrial fields where a high-temperature treatment is necessary, a plasma has been heretofore utilized as the high temperature-generating means, and since the conventional plasma-generating method utilizes an electric discharge, it has a basic problem in that a large amount of electric power is necessary, and further, the method is disadvantageous in that the means for generating the plasma is complicated and expensive.
Alternatively, a method in which a hydrocarbon is burnt by using a catalyst comprising specific metals in combination is known (see, for example, U.S. Pat. No. 3,842,015), Japanese Examined Patent Publication No. 61-20764 and Japanese Unexamined Patent Publication No. 63-283751), but this method is directed to the treatment of automobile exhaust gas or factory exhaust gas, and the combustion temperature is 1500.degree. C. at highest.